Heroes of swimming: Duke Kahanamoku

What's the best way to encourage children to feel confident in the water? A shallow, warm pool? Floats and arm bands? One-to-one lessons? The old Hawaiians were made of sterner stuff. When Duke Kahanamoku was a small boy, his uncles paddled him out into Honolulu harbour in an outrigger canoe and threw him in. Sink – or swim.

Duke swam – and he never really stopped. In fact, Duke would go on to be the greatest swimmer the world had ever seen. His skills as a waterman would earn him the friendship of presidents and heiresses. Duke rubbed shoulders with royalty. He became a film actor, playing alongside another "Duke", John Wayne, among others. President Kennedy learned the "Kahanamoku kick" as a way of improving his front crawl. Throughout Duke's whole life, though, he remained a humble, self-effacing man who never lost the chance to remind people that he wasn't a real duke at all – it was just a name, not a rank.

Kahanamoku was born in Hawaii in 1890. The islands were then an independent country, but within three years the last Hawaiian ruler, Queen Lili'uokalani, had been deposed by a coalition of American businessmen. Native Hawaiians found themselves largely powerless, with little land and few opportunities. What did remain to them was the ocean, where Hawaiians remained peerless watermen, in command of their environment in a way no haole could match.

In Honolulu, the Hawaiian "beach boys" staked claim to Waikiki, offering surfing lessons and canoe rides to the tourists who had begun to arrive in the Hawaiian islands. As soon as he was old enough, Duke dropped out of school and joined them. Fed a daily diet of ocean swims, surfing and canoeing, he gew to be 6'1" tall, broad shouldered and long legged. Like many great swimmers, Duke also had whopping feet: the size 13 flippers attached to the end of his legs can't have slowed him down much. It wasn't long before Duke could swim faster than any other beach boy. Just how fast he could go, people were about to discover.

In 1911, a 21-year-old Duke entered a swimming contest in Honolulu harbour. He won the 100 yards freestyle pretty much as expected. What may not have been expected was his time: 55.4 seconds. Duke had shaved 4.6 seconds off the world record. The reaction from the mainland ranged from initial sarcasm – "Did you use alarm clocks to time him?" they asked – to denial. The course must have been too short. The timing was inaccurate. Ocean currents must have aided his speed. In the end, the officials on the mainland simply refused to believe that an island boy could swim that quickly.

A year later, at the US Olympic trials, Duke broke the 200m freestyle world record despite making what one commentator called an "unconcerned" start, diving in a couple of seconds after everyone else. He was on his way to the Stockholm Games. There, he duly won the 100m freestyle – though not before falling asleep ahead of the final and having to be woken up to race. The start had to be delayed while a bleary-eyed Duke pulled on his costume and made his way to poolside.

Stockholm was only the start of Duke's Olympic career. The first world war meant there were no Games in 1916, but in 1920 in Antwerp he took gold in the 100m freestyle once more (beating a fellow Hawaiian, Pua Kealoha). In the 1924 Paris Games Duke had to settle for silver behind Johnny Weissmuller. Later, he liked to tell people, "It took Tarzan to beat me." Duke's brother Samuel won bronze, making it a clean sweep for the Americans. Even then the story wasn't over. At the age of 42, Duke played for the US water polo team at the 1932 Los Angeles Games. "I didn't do too well," he said, "but I guess you begin to slow down a little around 40."

All this would have been remarkable enough for someone who was fully focused on swimming – but Duke's first love was arguably surfing. He travelled the world giving surfing demonstrations, and is said to have brought the sport to Australia. Duke also rode one of the biggest, longest waves in surfing history in 1917, in a week when the rare giant waves known as "bluebirds" arrived in Hawaii. Duke, riding an old-school wooden olo board, 16 feet long and almost too heavy to carry, caught a huge bluebird off Waikiki and rode it for over 1,000 yards.

Duke later became sheriff of Honolulu and a worldwide ambassador for Hawaii and the aloha spirit. He died in Hawaii in 1968 at the age of 77. After a church service, a large crowd of mourners made their way across Honolulu to Waikiki. His ashes were scattered on the ocean. Today, if you're visiting Waikiki and want a surfing lesson, one of the best places to head for is Kahanamoku Beach.